1. Field of the Invention
The present invention relates generally to the field of biology. More particularly, it concerns transplantation and engraftment of xenogeneic hematopoietic stem cells without pre-conditioning.
2. Description of Related Art
Engrafting human hematopoietic stem cells (HSC) requires pre-conditioning immunodeficient recipients (e.g., mice) with a sub-lethal to lethal dose of total body irradiation (TBI). Such TBI pre-conditioning is shown to increase proliferation of HSCs through the expression of survival factors required for positive HSC engraftment. However, the side effects of TBI can include skeletal alterations, pneumonitis, proctitis, enteritis, colitis, esophagitis, dermatitis, and cerebellar damage. Unless death occurs, these side effects, which decrease the overall health of the recipient, often go unnoticed. Therefore, experimental engraftment results may be adversely reported when TBI is used.